First ‘dogmatic’ images The period 313 – 500 was foundational in the development of Christian art. In the previous two parts of this chapter we examined the develop-ment of church architecture during this period of legalization and as-cendency of Christianity to the status of official religion of the Roman Empire. We turn now to the development of Christian pictorial art during the period. Numerous heretical and political challenges as well as societal changes during the period of recognition influenced the visual representa-tions of the essential doctrinal beliefs of Christians. By the beginning of

the sixth century the basic dogmatic imagery of the Christian Church, with the exceptions of images of the crucifixion and some Marian themes, was established. There would be future variations but the essential thematic designs would remain constant throughout subsequent centuries. We are so certain, today, of our understanding of Jesus Christ and of what his role in history is that it is difficult for us to appreciate just how unclear it all was back in the early centuries. Basic issues remained disputed such as the nature of Jesus Christ –human or divine (or in what way or to what extent human or divine)?—and his relationship to God the Fa-ther (was Christ ‘begotten’ or ‘made’?). The political sphere also exerted its influence. With legalization and the patronage of the emperors came a tug of war over which had authority over the other. Was the emperor over the Church or the Church over the emperor? Also, the competition between the new faith and traditional paganism challenged Christianity to define itself visually relative to the old pagan beliefs. How was it different; how was it similar? There was even the prob-lem of how to depict Christ. What should he look like? What,

in fact, had he looked like? Is it proper and right that he be depicted in images? We will leave the controversy over the use of images in worship, and the question as to whether Christ and the saints should be depicted, until we take up the matter of the iconoclastic controversy. For now, it is enough to say that while Christian writers often hotly criticized the pa-gans for the worship of gold and silver idols they seemed to not take much notice of the prominent use of images in Christian worship during the 4th and 5th centuries. (Extravagant decoration of churches was criti-cized but not so much the use of images.) The legalization of Christianity seemed to beg for some kind of impressive art if for no other reason than to instruct new initiates in ‘orthodox’ Christianity. Perhaps that is the possible explanation for the mostly mute response of the Christian theo-logians to the surge in the production of religious images. We don’t have a great deal of liturgical art –decoration in churches-- to examine created before 350. We assume that some works existed and there is evidence that there were some impressive frescos [152] but, unfortunately, those are long gone and so for the period imme-

The apse fresco indicated here is conjecture based upon later draw-ings. The upper image is of the ‘traditio legis’ type within a garden

152 Original altar and apse of old St Peter's, Rome; ca. 350.

<http://inillotempore.com/blog/pivot/entry.php?id=632>

diately following legalization we have to be content with surveying the final phase in the production of funerary or catacomb art or relying on textural references. We will proceed by discussing the probable reasons for the intro-duction of new subjects during this period. In competition with paganism The magic wand One of the most interesting of the new subjects was actually introduced in the 3rd century, a little earlier than the period we are currently explor-ing. It is not strictly speaking a dogmatic image although it firmly estab-

lished for history our understanding of the human personality of Jesus. We see the subject in catacomb paintings and on sarcophagi: Christ working his miracles using a magic wand[153]. Nothing, of course, is mentioned in scripture –the Gospels—of Christ ever using a wand to do magic. The inclusion of a magic wand in the storytelling paintings and carvings therefore intrigues us and so we search for a reason.1 Magic was an important aspect of the ancient world; there were rituals and incantations for nearly everything, but most especially for health concerns.2 As well, the representations of Christ’s mira-

cle cures were ubiquitous in funerary art, on objects of everyday use, and ecclesiastical objects. In fact, the miracle stories could be viewed as the one unifying theme among the several seemingly disjointed pictorial presentations in early Christian art during the third and first half of the fourth century. Depictions of Christ using a magic wand to cure people may be explained relative to the magic worked by pagan magicians who also used magic wands. The magic wand seems to invite the comparison. There were, however, some critical differences between Christ’s magic tricks and the magicians’. First, Christ took no payment for a miraculous cure. He did not perform a miracle as entertainment for profit. His pur-pose, unlike the magicians, was to lead people to a fuller, better life. Sec-ondly, He performed miraculous cures without using spells and incanta-tions which were essential aspects of ancient magic rituals. Rather, Jesus did miracles in his own name. Thirdly, magicians’ magic tricks were illu-sions but Christ’s miracles were real and permanent.3

Also –aside and apart from magicians’ magic and the use of

153 The Raising of Lazarus , sarcophagus carving, Lateran Basilicaca. 340; Musei Vaticani, Rome.

Christ raises Lazarus with the aid

of a magic wand.

Thomas F. Mathews, The Clash of Gods; a Reinterpretation of Early Christian Art, Revised and Expanded edition, (Princeton, Princeton University Press 2003) p 55

wand, and relative to the pagan gods of healing-- Christ had a better, more appealing bed-side manner. Often he is “seen in Christian imagery walking among his people, touching, stroking, comforting, pressing his warm and life-giving hands on them, and working a very visible magic."4

Personal, compassionate human touch was never part of the representa-tion of the pagan gods associated with curing. It was central in the depic-tion of Christ’s miracles[154]. Even when he id shown using the wand hi is seen among the common people. This image of the personal, compas-sionate Christ was a welcome relief in the world of late antiquity when so much of life was dehumanizing. Clearly, Christ’s magic and healing

power was better than what the magicians and pagan gods could offer. The inclusion of a magic wand in depictions of Christ effecting cures had a relatively short life, disappear-ing from Christian imagery once paganism had sufficiently faded as a serious official competitor. The image of a com-passionate and personal Christ, however, defined him for all future generations. Christ seemingly inherited his magic powers from his pre-

cursor in the Old Testament, Moses, who is sometimes shown in Chris-tian art of the same period also wielding a magic wand in, for example, parting the red sea using his staff and -in the desert- commanding water to flow from a rock by hitting the stone, also with his staff.5

The theme of the superiority of Christ’s magic over that of sorcer-ers and the pagan gods may also be partly responsible for the appearance in Christian art of the story of the Adoration of the Three Magi[155]. Magi were knowledgeable experts when it came to evil spirits and magic. It is possible that the appearance and popularity of the magi story during this time of intense competition with paganism was a signal to the pagan world that the power of the old gods –the ‘demons’ as the Christians called them- had finally met its match in Jesus Christ.6 The experts –the magi– had recognized and officially declared Christ the victor. The scene of the adoration of the magi became iconic in Christian art.

Thomas F. Mathews, The Clash of Gods; a Reinterpretation of Early Christian Art, Revised and Expanded edition, (Princeton, Princeton University Press 2003) p 70

<http://www.catholic-convert.com/Portals/0/Moses-Peter%20sm.jpg>

154 Sarcophagus Fragment with Miracle Scenes , ca 300-310; Museo Nazionale delle Terme, Rome

(from left to right) the Cure of the Woman with Issue of Blood, the Sermon on the Mount, Cure of the Paralytic, and the Cure of the Leper. In each cure image Christ touches the person with his hand. The use of a magic wand eventu-ally disappears from images of Christ working miracles once pa-ganism had lost its official appeal.

156 (top) Moses Using a Magic Wand to Cause Water to Flow from Rock, Roman catacomb ca. 4th c.

155 (above) Adoration of the Magi, Christian sarcophagus, ca.

The subject may have appeared in

the 4th c. in celebration of the

victory of the New Law of Christ

over the old law of the

‘demons’ (pagan gods of ancient

Greece and Rome).

Contra Arianism Arius, a priest of North Africa, propounded a heresy that was one of the first to plague the Church following Constantine’s recognition of the Christian religion in 313. Debate centered chiefly in the Eastern Roman Empire, in Alexandria and Antioch, Egypt and Syria. Briefly, Arius taught that Jesus was not God as the Father was God but rather was made by the Father and therefore had a beginning. The Son, therefore, had not always existed (was not co-eternal with the Father). It became a serious challenge to the faith with perhaps more than half of the bishops identi-

fiably Arian at one point.7 The disunity caused by the uproar in the East was too much for the emperor to ignore and so he called a Church council (the First Council of Nicaea, 325) that met and drafted a creedal formula that condemned Arius and upheld that Jesus the Christ was of the “same substance” as the Father and was “eternally begotten” of the Father, not made by the Father. The eternal divine Logos took on human flesh and became man in Jesus Christ. The halo and aureole/mandorla To stress the divinity of Jesus, a symbolic design element was employed that had no precursor in Greek and Roman art but seems to have been imported from the orient. When we now see a figure repre-

sented with a halo[159 behind the head of a painted or sculpted image we instantly identify the figure as holy –or divine. That symbol of holiness or divinity appeared in Christian art in the second half of the 4th century. The halo, however, had its origins in 2nd century India and central Asia in representations of Buddha[158]. At first, the halo was reserved to Christ but eventually was applied to representations of any saint and even some-times the emperor. Christ’s halo became distinguishable from others by the addition of three arms of a cross (or three rays of light) inscribed on the round shape behind his head. Another symbolic shape, the aureole and mandorla, surrounded the entire figure. It appeared in Christian art at about the same time as the halo. During this period it is always an indication of divinity. Christ is represented standing or sitting full-figure in front of an oval shape. Often the figure of Christ oversteps the edge of the shape. The mandorla is of-ten alleged by some art historians to be derived from the imago clipeata or shield image --an imperial association-- but, like the halo, is really of

157 (below) Gandhara Buddha, 1st-2nd c. A.D., Tokyo National Museum

<http://commons.wikimedia.org/wiki/File:Gandhara_Buddha_%28tnm%29.jpeg> Wikipedia:en:User:World Imaging (talk)|World Imaging (talk)]] at the English Wikipedia project.

158 (top right) Christ with Halo, Catacomb of Commodilla, Rome, late 4th c.

159 (right) Christ in Glory, mo-saic, Catacomb of Domitilla, Rome, 4th c.

Christ is fully surrounded by a spherical aureole.

Buddhist origin.8 Halo and mandorla act as the visual clue that the ortho-dox belief is that Christ is divine. Majestas Domini (Christ in Glory) The Majesta Domini (Christ in Glory) the dogmatic image that employs the aureole or mandorla shape to communicate Christ’s divine nature. In the image, Christ is presented in total glory in front of a numinous burst of either golden or multi-colored light (an aureole) or sharply defined mandorla (oval shape) of many colors. In this way the Second Person of the Blessed Trinity is depicted as the all-powerful Ruler of the universe. Sometimes, Christ is seated on a symbolic globe of the cosmos[160]. Whether seated or standing he is almost always shown full figure. To the sides of the central figure often appear the figurative symbols of the four evangelists or writers of the four gospels, Matthew (winged human), Mark (winged lion), Luke (winged ox or bull), and John (eagle). The earliest Majestas Domini image in a church setting that we know of is a mid 5th century small apse mosaic in the chapel of Hosios David attached to a monastery in Thessaloniki[161]. A young Christ ap-pears in front of a radiantly colored aureole, seated on a rainbow. Four abbreviated creatures –the symbols of the four evangelists- flank the cen-tral figure of Christ and are partially overlapped by the transparent aure-

oleaureole. Below Christ the four rivers of paradise flow from a hill. Christ holds a scroll that reads “I am the spring of living water.” The scene represents Chapter 4 of the Biblical Book of Revelation. The writer of that book, St. John the Evangelist, is shown seated to the far right in the mosaic, calmly writing what he is seeing. The figure seen cringing and turning away in terror on the far left, hiding from the vision, is the Old

161 The Vision of Ezekiel, apse mosaic in Blessed David Chapel, Thessalonica, ca. 425-50.

160 Christ in Glory, ca. 1220, Museo d’Arta, Barcelona, Spain

Buddhist origin.8 Halo and mandorla act as the visual clue that the ortho-dox belief is that Christ is divine. Majestas Domini (Christ in Glory) The Majesta Domini (Christ in Glory) the dogmatic image that employs the aureole or mandorla shape to communicate Christ’s divine nature. In the image, Christ is presented in total glory in front of a numinous burst of either golden or multi-colored light (an aureole) or sharply defined mandorla (oval shape) of many colors. In this way the Second Person of the Blessed Trinity is depicted as the all-powerful Ruler of the universe. Sometimes, Christ is seated on a symbolic globe of the cosmos[160]. Whether seated or standing he is almost always shown full figure. To the sides of the central figure often appear the figurative symbols of the four evangelists or writers of the four gospels, Matthew (winged human), Mark (winged lion), Luke (winged ox or bull), and John (eagle). The earliest Majestas Domini image in a church setting that we

know of is a mid 5th century small apse mosaic in the chapel of Hosios David attached to a monastery in Thessaloniki[161]. A young Christ ap-pears in front of a radiantly colored aureole, seated on a rainbow. Four abbreviated creatures –the symbols of the four evangelists- flank the cen-tral figure of Christ and are partially overlapped by the transparent aure-ole. Below Christ the four rivers of paradise flow from a hill. Christ holds a scroll that reads “I am the spring of living water.” The scene represents Chapter 4 of the Biblical Book of Revelation. The writer of that book, St. John the Evangelist, is shown seated to the far right in the mosaic, calmly writing what he is seeing. The figure seen cringing and turning away in terror on the far left, hiding from the vision, is the Old Testament prophet, Ezekial. Ezekial had a similar vision to that de-scribed by John in Revelation except the abbreviated creatures were four headed beasts known as tetramorphs. Depicted in this mosaic are the two contrasting images favored by the Eastern and Western branches of Christianity. The Old Testament vision of the god-head, Ezekial’s vision,

162 The Adoration of the Three Magi, left side of triumphal arch mosaic, Santa Maria Maggiore, 4th c.

was favored by the Eastern Church. The New Testament vision revealed to St. John was favored by the Western Church9. The Hosios David (Blessed David) type Christ in Glory is as-sumed to have been a popular image in the churches of Constantinople because they were frequently deployed in the apses of Egypt and Arme-nia. Some survive in Cappadocia. Constantinople, as the Eastern capital would have influenced the decoration of these churches10. At the time, the image was known as the theandric or god-man image11. The Majestas Domini became one of the foundational dogmatic image types in Christian art as it depicts Christ as a man but radiating all his divine glory as the absolute ruler of all the universe. We will find the

image deployed in nearly every period even down to the present.

The Theotokos (Mother of God or God Bearer) Images we see today of Mary seated on a throne holding the Child Jesus on her lap originated in the late fourth century and probably derives from an ancient Egyptian image of the goddess Isis holding the god Horus on her lap and suckling him. But the Christian dogmatic

basis of the imagery clearly dates to the period following the Council of Ephesus (431) which proclaimed the doctrine that Jesus was one per-son consisting of two complete na-tures –divine and human- unified but maintaining the fullness of each. The Virgin Mary, the Council proclaimed, was to be called The-otokos (God bearer) because she bore and gave birth to God as a man. A beautiful 5th century mosaic program[162] that was created for the Basilica of Santa Maria Maggiore in Rome celebrates the dogma. Included are images that show Mary’s exalted status. On the

left side of the triumphal arch the mother is depicted sitting on a throne next to her young son who is seated on an oversized throne, a symbol of his divinity. Christ is attended to by heavenly angels. The context of the scene is the adoration of the magi, who are represented to the right of Mary and acknowledge for all the world the coming of God to man. The star of the magi appears in the center of the group of angels behind the child Jesus. The symbolism of all this is unmistakable: Mary is the The-otokos or God Bearer; she is the ark of the new covenant, Jesus Christ -

163 (below, top) Sarcophagus of Junius Bassus , marble, ca. 359, Museo Storico del Tesoro della Basilica di San Pietro

164 (above, bottom) Christ Be-fore Pilate, Sarcophagus of Junius Bassus , marble, ca. 359, Museo Storico del Tesoro della Basilica di San Pietro

the Word of God made man. This image would be abbreviated in subse-quent depictions with the mother regally arrayed on a throne and holding the child in her lap. Her lap became the earthy throne of her son. The en-throned Madonna with Child became visual shorthand for the doctrine of the Incarnation.

Anti-imperial themes Christ before Pilate; Peter and Paul before Nero Several subjects appeared during the 4th and 5th centuries that contrasted the humble authority of Christ with that of arrogant earthly power. No

doubt the subjects were a reaction to the horri-fying persecution initiated by Diocletian at the end of the 3rd century and which continued on into the beginning of the fourth, ending with the ascendency of Constantine the Great. The Great Persecution had come as a shock to the Christians, many of whom had risen to high levels in the imperial court and in the military during the previous period of relative peace. These new subjects communicated the hope of the eventual triumph of Christ since his author-ity came from his Father in heaven. It is interesting that scenes of Christ’s pas-sion and crucifixion are absent from the earli-

est Christian art. We examined in the last chapter the possible reasons for the absence of the cross in the early centuries. The crucifixion is not rep-resented during the following period of recognition, either, but is ap-proached obliquely through peripheral scenes from the passion such as the arrest of Christ and his standing before Pilate.[164] It is as if the ac-tual point of the appearance of those scenes was other than relating the actual story of the passion. If we move beyond a mere literal reading of, for example, the story of Pilate’s interview of Christ, we find that Jesus, in his silent humility, actually stands up to the emperor’s representative

165 The Emperor’s Adventus, Arch of Galerius, Thessalonica, 300.

166 Christ’s Triumphal Entry into Jerusalem from a sarcopha-gus with scenes from the Lives of Saint Pater and Christ, marble, early 300s (with modern restora-tion), Roman

and trumps arrogant imperial power by rising from the dead on Easter Sunday12. The message would not have been lost on the Christians who lived through the last great persecution of the Church. The memory of that persecution would live on for some time even after its sudden end and eventual legalization of the faith. The promise of ultimate reward for faithfulness to Christ in the face of the most brutal of earthly persecutions would sustain Christians down through the centuries.

Triumphal Entry into Jerusalem The gospel story of Jesus’ triumphal entry into Jerusalem to celebrate the Jewish Passover probably also appeared in Christian art in reaction to the Great Persecution. In this case the scene strongly contrasts Christ’s hum-ble procession into Jerusalem on the back of a donkey with the show of imperial power displayed in scenes of the emperor’s adventus into Rome in a royal chariot or cart.[165] Both scenes show us a procession but Christ enters Jerusalem to be sacrificed for the sins of many while the emperor enters Rome to lay claim to the city. At first glance the Entry[166] images seem similar to the adven-tus scenes but the message is in the details13. There is the donkey, a hum-ble beast of burden, which contrasts with the proud imperial chariot of the emperor. Christ wears the garb of a philosopher indicating a person who deals in higher, spiritual issues while the emperor wears the uniform of a warrior general who deals in earthly blood and guts. Christ is accom-panied by his apostles who also wear philosophers’ clothing. The em-peror is escorted by contingents of armed infantry and cavalry. Crowds of people wildly greet Christ, spreading cloaks on the ground before him and waving palms. There are no crowds greeting the emperor. Christ greets the people with a blessing. The emperor stares straight ahead, not condescending to acknowledge anyone or anything. The message is clear: Christ’s power is so far above earthly power that no impressive display is necessary. Even after earthly power has its way with Christ on Good Friday he will triumphantly rise from the grave on Easter Sunday. The crucified and risen Lord is the hope of Christians. The visual motif of the Triumphal Entry of Christ into Jerusalem may actually have derived from formulaic homecoming or hunting scenes of gentlemen common on pagan sarcophagi of Roman noble-

167 Gentleman’s Homecoming, sarcophagus, early 4th c., Berlin

Such homecoming scenes may be

the design source for the Christian

story of Christ’s triumphal entry

into the city of Jerusalem the

weekend before his crucifixion.

Thomas F. Mathews, The Clash of Gods; a Reinterpretation of Early Christian Art, Revised and Expanded edition, (Princeton, Princeton University Press 2003)

men.14[167] It is also on the sarcoph-agi of Christian noblemen where we first find the Entry scenes. Imperial adventus scenes, on the other hand, never appear on sarcophagi. Hunting and homecoming scenes reflected the life style of noblemen and so were common motifs on their sarcophagi. The motif called for the nobleman to be depicted as a hunter on horseback with a hunting dog sniffing the ground under the horse or a noble-man returning home to his estate

while his servants harvest an abundant crop of, for exam-ple, olives. This was the same kind of formula as we find in the Entry scene where Christ rides a donkey with a foal underneath. The trees in harvesting scenes on the coffins of the pagan noblemen may have provided the models for the palm trees in the Entry compositions. The harvesters harvesting the olives are the models for the citizens of Jerusalem gathering palms in palm trees. With a little reworking, sculptors transformed the hunting and harvesting scenes found on the sarcophagi of pagan Ro-man noblemen into the Christian Entry design found on the sarcophagi of Christian noblemen. The Triumphal Entry of Christ into Jerusalem, in story and in image has become iconic, standing in pointed op-position to all worldly power.

Dominus legem dat Petro (the Lord gives the law to Peter).

A most interesting newcomer in Christian art during the fourth century was the image of Christ seated -or standing- and handing a scroll to St. Peter in the presence of St. Paul.[168] Sometimes both apostles are re-ceiving scrolls. The depiction has come to be known as the Dominus legem dat Petro or, the Lord gives the law to Peter. It also is known as the traditio legis (giving of the law) but that title we will reserve for a composition that includes all the apostles. In some examples of Dominus legem dat Petro Christ sits or stands with his feet on Caelus, the Roman sky god. The image is, of course, fictional; it is not historical narrative –the scene never happened. But it is a doctrinal and symbolic image that proclaims that the new law of Christ has defeated the world of the ancient gods and goddesses (represented by Caelus) and all the worldly powers

169Traditio Legis , front of a sarcophagus in the Museo Arche-ologico, Ravenna, 5th c. In this image Christ stands upon a hill in paradise. A husband and wife are shown to the far right and left.

168 Dominus legem dat Petro , detail from the sarcophagus of Junius Bassus, marble, ca. 359, Museo Storico del Tesoro della Basilica di San Pietro

170Distribution of largesse, detail of the north frieze of the Arch of Constantine, Rome Italy, 312-315

Thomas F. Mathews, The Clash of Gods; a Reinterpretation of Early Christian Art, Revised and Expanded edition, (Princeton, Princeton University Press 2003) p 130

that invoked them. The two apostles symbolize the proclamation of the new law to the entire world for Peter symbolizes the Jewish wing of the Church and Paul, the Gentile wing. The new law is, therefore, for every-one –Jew and Gentile.

What is this ‘new law’ of Christ? To the Apostolic Fathers of the Church –the earliest Christian preachers and writers- it is new knowl-edge, a fresh life, and immortality. It is the abandonment of idolatry and union with Christ through whom we receive new and everlasting life with God. Through Christ God has called us from darkness to light, from ignorance to knowledge15; He has rescued us from the darkness of error.16

Does the Dominus legem dat Petro show forth an anti imperial theme? Yes, because it represents Christ as a law-giver. Only rulers –emperors- proclaim laws. Christ is clearly presented as a law giver and as such is in competition with the imperial authority. The message, of course, is that God’s law supersedes all earthly laws especially laws instituted with invocations of the pagan gods. God’s law will always ultimately tri-umph. The truth of that article of faith must certainly have been evident to the 4th century Christians who had recently emerged from the dark night of the Great Persecution to the bright light of recognition as the official religion of the Roman Empire.

There are two possible sources for the pictorial composition of the

Dominus legem dat Petro. The first could be Roman imperial iconogra-

phy of emperors distributing largesse[170], receiving bounty, sitting in

judgment, or distributing aid, instructions or awards to approaching fig-

ures.17 In these scenes the emperor is seen sitting or standing and pre-

senting various objects or scrolls to figures lined-up or ‘stacked-up’ to

his right and left.

Another possible source for the Dominus legem dat Petro is the

type of image carved on sarcophagi that suggested the education and

171 Deceased as philosopher or as an educated Roman , pa-gan sarcophagus, 4th c.

learning of the deceased[171]. The seated figure was depicted hold-

ing and reading a scroll, sometimes with others standing or seated

around him. The fact that the image of the ‘deceased as philosopher’

disappears from Christian sarcophagi at about same time that the

Dominus legem dat Petro motif shows up on them suggests the pagan

scene was replaced with the Christian one.

(load the next pdf. file to continue)

______________________________

1 Thomas F. Mathews, The Clash of Gods; a Reinterpretation of

Early Christian Art, Revised and Expanded edition, (Princeton,

Princeton University Press 2003) p 54 2 Mathews 66 3 Mathews 67 4 Mathews 92 5 Mathews 72 6 Mathews 84 7 St. Jerome: "The whole world groaned and marvelled to find itself

Arian." 8 Mathews 117 9 James Snyder, Medieval Art, Painting-Sculpture-Architecture, 4th-

14th Century, (New York, Harry N. Abrams, Inc. 1989) p 107-08 10 Mathews 116 11 Mathews 117 12 Mathews 91 13 Mathews 25 14 Mathews 33

15 1 Clement 36, 2

16 1 Clement 59, 2

17 Traditio Legis, October 7, 6:09, 2010 <a href="http://

encyclopedia.jrank.org/articles/pages/3501/Traditio-Legis.html">Traditio